Apache APISIX: the body_schema check in request-validation plugin can be bypassed

published 2022-03-28 4 y ago modified 2026-09-08 2 mo ago also BIT-apisix-2022-25757 , EUVD-2022-30412

cvss: 9.8; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 2.5%; EPSS 2.5% chance of exploitation in 30 days, percentile 84%
public exploits: 0; none known

In Apache APISIX before 2.13.0, when decoding JSON with duplicate keys, lua-cjson will choose the last occurred value as the result. By passing a JSON with a duplicate key, the attacker can bypass the body_schema validation in the request-validation plugin. For example, `{"string_payload":"bad","string_payload":"good"}` can be used to hide the "bad" input. Systems satisfy three conditions below are affected by this attack: 1. use body_schema validation in the request-validation plugin 2. upstream application uses a special JSON library that chooses the first occurred value, like jsoniter or gojay 3. upstream application does not validate the input anymore. The fix in APISIX is to re-encode the validated JSON input back into the request body at the side of APISIX. Improper Input Validation vulnerability in __COMPONENT__ of Apache APISIX allows an attacker to __IMPACT__. This issue affects Apache APISIX Apache APISIX version 2.12.1 and prior versions.

Patch / fix

fixed in 2

bitnami apisix 2.13.0
apache apisix 2.13.0

Exploit prediction

2.48% chance of exploitation in the next 30 days, higher than 84% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD	2.0	6.8	AV:N/AC:M/Au:N/C:P/I:P/A:P
OSV	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem	package	affected	fixed in
bitnami	apisix	<2.13.0	2.13.0

Affected products

Apache Software Foundation Apache APISIX

Classification

Weakness

CWE-20 Improper Input Validation

References

lists.apache.org /thread/03vd2j81krxmpz6xo8p1dl642flpo6fv
mailing-list, vendor-advisory, advisory
openwall.com /lists/oss-security/2022/03/28/2
mailing-list, third-party-advisory, advisory
nvd.nist.gov /vuln/detail/CVE-2022-25757
web

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary